A cooling circuit of an internal combustion engine and having a plurality of sub-circuits for a motor vehicle with a device for operating such a coolant circuit, in particular for control of the coolant flow in the individual sub-circuits.
Such coolant circuits are preferably used for thermal management of an internal combustion engine, with the coolant flow being dispersed between the sub-circuits of the coolant circuit by a device for operating the coolant circuit such as to establish an optimum operating temperature of the internal combustion engine in a quickest possible way.
DE 602 09 019 T2 discloses a control valve for a cooling circuit of an internal combustion engine, with coolant flowing through the circuit which has a first branch which contains a radiator of the engine, a second branch that constitutes a branch line of the radiator, and one or more third branches, each of which having at least one hot-air generator for heating the vehicle cabin. The control valve is formed as a body with a fluid inlet, a first outlet connected with the first branch, a second outlet connected to the second branch, and at least one third outlet connected to the third branch, wherein an adjustment member is arranged rotatably in the body so as to selectively control the outlets. By rotating the adjustment member in a given direction, a defined sequence of positions can be taken. In a first position the first outlet, connected to the branch line, is open; in a second position the second outlet, connected with the second branch, is open in addition to the first outlet; in a third position only the second outlet is open; in a fourth position the second and the third outlet, connected with the third branch, is open; in a fifth position all outlets are open; in a sixth position the first and the third outlet are open; and in a seventh position the first or the third outlet are open. Furthermore, the adjustment member may also assume a position in which no outlet is open.
Such a control valve is disadvantageous because the sequence of possible positions is rigidly predefined. Thus, positional changes are oftentimes required, when the coolant requirements change, so that the adjustment member has to be rotated accordingly frequently. As the control valve realized many functions by using only one adjustment member, the control valve is complex in structure requiring a plurality of components, causing problems in connection with wear and tightness.
DE 103 06 094 A1 discloses a combustion engine cooling system for a vehicle with a coolant pump, an engine circuit for conducting the coolant through the engine, a radiator circuit for conducting the coolant through the radiator, a bypass circuit for returning the coolant to the engine circuit without passing through the radiator circuit, and a heater circuit for conducting the coolant through the heater core. A rotary valve for switching the coolant is described and includes a valve body having an inlet port and a plurality of outlet ports, with the outlet ports including a radiator port for conducting the coolant in a radiator circuit, a bypass port for conducting the coolant in a bypass circuit, and a heater port for conducting the coolant in a heater circuit. The valve body further includes a rotationally supported flow diverter with a plurality of fluid passages providing predetermined flow paths between the inlet port and the outlet ports in response to a rotational position of the flow diverter. The predetermined flow paths include a first operating mode for distributing the coolant to the radiator port and the heater port while blocking the bypass port at the same time, a second operating mode for distributing the coolant to the bypass port while blocking coolant from the radiator port and the heater port at the same time, a third operating mode for distributing the coolant to the heater port while blocking the coolant from the radiator port and the bypass port, and a fourth operating mode for distributing the coolant to the radiator port and to the bypass port while blocking the coolant from the heater port at the same time.
Such a combustion engine cooling system is disadvantageous because the structure of the rotary valve results in a restriction of the controllable circuits. Incorporation of further circuits necessarily leads to a poorer control of the individual circuits. As a result, the coolant temperature can no longer be adjusted with sufficient precision and speed to the desired value, diminishing the ability of the internal combustion engine to reach the operating temperature.